Evaluation of surface lead migration in pre-1950 homes: an on-site hand-held X-ray fluorescence spectroscopy study.

Lead-paint concentration on specific surfaces (walls, floors, windowsills, etc.) in pre-1950 homes was measured using a hand-held X-ray fluorescence (XRF) spectroscope. Surface lead was examined concomitantly using wipe sampling and XRF Lead was detected in all 147 samples via XRF; and of these, 29 ( 20%) revealed surface lead contamination via wipe sampling. Seventeen of the positive wipe samples were collected from surfaces with clear visible defects, while 12 samples were collected from surfaces with no visible defects. Curve fitting of surface to lead-paint concentrations generated empirical relationships that described the migration of lead from inner layers at locations with and without visible defects. Curve fitting indicated that lead migration was power-law dependent when surface defects were present and linear when no defects were visible. These correlations may assist surveyors in predicting lead migration to the surface from lead-paint concentration measured with a hand-held XRF instrument.

Sleeping Beauty transposon screen identifies signaling modules that cooperate with STAT5 activation to induce B-cell acute lymphoblastic leukemia.

Signal transducer and activator of transcription 5 (STAT5) activation occurs frequently in human progenitor B-cell acute lymphoblastic leukemia (B-ALL). To identify gene alterations that cooperate with STAT5 activation to initiate leukemia, we crossed mice expressing a constitutively active form of STAT5 (Stat5b-CA) with mice in which a mutagenic Sleeping Beauty transposon (T2/Onc) was mobilized only in B cells. Stat5b-CA mice typically do not develop B-ALL (<2% penetrance); in contrast, 89% of Stat5b-CA mice in which the T2/Onc transposon had been mobilized died of B-ALL by 3 months of age. High-throughput sequencing approaches were used to identify genes frequently targeted by the T2/Onc transposon; these included Sos1 (74%), Kdm2a (35%), Jak1 (26%), Bmi1 (19%), Prdm14 or Ncoa2 (13%), Cdkn2a (10%), Ikzf1 (8%), Caap1 (6%) and Klf3 (6%). Collectively, these mutations target three major cellular processes: (i) the Janus kinase/STAT5 pathway (ii) progenitor B-cell differentiation and (iii) the CDKN2A tumor-suppressor pathway. Transposon insertions typically resulted in altered expression of these genes, as well as downstream pathways including STAT5, extracellular signal-regulated kinase (Erk) and p38. Importantly, expression of Sos1 and Kdm2a, and activation of p38, correlated with survival, further underscoring the role these genes and associated pathways have in B-ALL.

Double-blind, placebo-controlled study of ranitidine for gastroesophageal reflux symptoms during pregnancy.

OBJECTIVE: To determine whether ranitidine (Zantac) taken once or twice daily is effective for relieving symptoms of gastroesophageal reflux among pregnant women who had failed conservative measures. METHODS: Volunteers with heartburn despite antacids were sought among our obstetrics clinic population for this double-blind, placebo-controlled, triple crossover trial. After a baseline week, 20 patients were randomized to receive the three following weekly regimens: ranitidine 150 mg twice daily, placebo in the morning and ranitidine 150 mg in the evening, or placebo twice daily. Daily scores on symptom diaries, global assessments, and number of antacids taken were compared among the 18 patients completing the study. RESULTS: The twice-daily dosage of ranitidine was the only regimen found to reduce heartburn symptoms when compared with the baseline (P < .001) or a placebo (P < .01). Compared with ranitidine taken once daily, the twice-daily dosing prompted less need for antacid tablets compared with the placebo (P < .05 versus P > .05) and to the baseline (P < .001 versus P < .05). The average reduction of heartburn severity using twice-daily ranitidine was 55.6% when compared with baseline (95% confidence interval [CI] 34.8%, 76.5%) was 44.2% when compared with placebo (95% CI 15.4%, 72.9%). CONCLUSION: This study indicates the efficacy of ranitidine 150 mg taken twice daily, rather than once daily, for relief of gastroesophageal reflux symptoms during pregnancy.

Development of a 12 element annular array transducer for realtime ultrasound imaging.

While the recent proliferation of ultrasound scanners based on annular array transducers has attracted widespread attention, very little published information is available on the physics, design criteria, and signal processing aspects of these instruments. In this paper, the first of a two part report, we describe the development and characterization of an annular array transducer for realtime medical imaging. Theoretical modeling of the pulsed fields of annular arrays is used to study and optimize array parameters. The factors which affect resolution and contrast in imaging--beam width, sidelobe levels, number of annuli, depth of field, and delay quantization--are discussed. A 12 element, 4.5 MHz, 30 mm design is adopted. Theoretical predictions showed excellent agreement with device measurements over a range of f-numbers (local/length/diameter) from f/1 to f/6.7 (30 to 200 mm range). Focusing to f/1 is an important advance in the state-of-the-art. A two transmit zone, dynamic receive configuration of array operation to exploit the f/1 focusing ability is proposed for realtime imaging.

A digital annular array prototype scanner for realtime ultrasound imaging.

The use of annular array transducers in diagnostic ultrasound applications is growing. The development of this equipment raises a number of questions concerning both the role these systems will play in the clinic and how the annular array can be best implemented in an ultrasound scanner. In this paper, we will build on the results of the previous companion paper to describe the development of a 12 element 30 mm diameter 4.5 MHz laboratory prototype scanner. The mechanical probe and probe acoustics are discussed and a unique digital receive beamformer (DRB) and signal processor are described. Focusing down to an f-number (focal length/diameter) of 0.9 is demonstrated. Measured angular beamwidths of 0.62 degrees at -6 dB and 2.8 degrees at -50 dB are in good agreement with theoretical predictions. Images of phantoms and normal volunteers showed exceptional resolution with little variation in the fine speckle texture as a function of depth. The effect of the number of transmit focal zones on image quality is demonstrated.

Patterns of uterine activity. Using oxytocin after intracervical PGE2.

OBJECTIVE: To compare patterns of uterine activity from low-dose oxytocin begun immediately or six hours after intracervical placement of prostaglandin E2 (PGE2) gel for the induction of labor. STUDY DESIGN: A total of 50 nonlaboring women at term with an unfavorable cervix (Bishop score < or = 4) were given a 0.5-mg dose of PGE2 gel. Each was then randomized either to be observed or to receive a low dose of oxytocin (2 mU/min, increased by 2 mU/min at 30-minute intervals, as necessary). After the six-hour observation, the patient was reexamined, and a low dose of oxytocin was either begun or continued. An adequate sample size (21 per group) was calculated for evaluating uterine activity changes. Comparisons were made using chi 2 testing, Student's t test and analysis of variance, as appropriate. RESULTS: There were no differences between the two groups in maternal race, gestational age, predose Bishop score, predose uterine activity or indication for induction. Uterine contractions became more frequent (P < .01) and were judged to be more intense (P < .02) and earlier when oxytocin was used immediately after PGE2 placement. No uterine hyperstimulation or abnormal fetal heart rate pattern was observed that required discontinuation of the oxytocin. The percentages of cases delivering vaginally within 24, 36 and 48 hours were greater when oxytocin was begun immediately in nullipara (P < .01). CONCLUSION: Low-dose oxytocin may be started immediately after instilling intracervical PGE2, with shortened time until the onset of adequate contractions.

Isolation and characterization of an acyl-CoA thioesterase from dark-grown Euglena gracilis.

An acyl-CoA hydrolase from dark-grown Euglena gracilis Z was purified 700-fold by subjecting the 105,000g supernatant of the cell-free extract to (NH4)2SO4 precipitation, acid precipitation, calcium phosphate gel treatment, gel filtration on Sephadex G-100, and chromatography on QAE-Sephadex, hydroxylapatite, and CM-Sephadex. Polyacrylamide disc gel electrophoresis of the purified enzyme showed a major protein band (greater than 80%) which contained thioesterase activity and a minor protein band with no thioesterase activity. Molecular weight estimated by gel filtration was 37,000 and sodium dodecyl sulfate-electrophoresis showed one major band (greater than 80%) corresponding to a molecular weight of 37,000 and a minor band of molecular weight 32,000, suggesting that the enzyme was monomeric. The pH optimum of the purified enzyme progressively increased with the chain length of the substrate, with hexanoyl-CoA showing a pH optimum at 4.5 and stearoyl-CoA at 7.0. The rate of hydrolysis of acyl-CoA showed a nonlinear dependence on protein concentration, and bovine serum albumin overcame this effect as well as stimulated the rate. The extent of stimulation by albumin increased with chain length of the substrate up to lauroyl-CoA and then decreased as chain length increased; albumin inhibited the hydrolysis of stearoyl-CoA. This enzyme hydrolyzed CoA esters of C6 to C18 fatty acids with a maximal rate of 17 mumol min-1 mg protein-1 for C14. Typical substrate saturation patterns were obtained with all substrates except that high concentrations were inhibitory. Studies on the effect of pH on the apparent Km and Vmax values for octanoyl-CoA, lauroyl-CoA, and palmitoyl-CoA showed that in all cases Vmax was greatest and Km was lowest at the respective pH optima. Active-serine-directed reagents severely inhibited the thioesterase activity, suggesting the participation of an active serine residue in catalysis; thiol-directed reagents were not effective inhibitors. Diethylpyrocarbonate also inhibited the enzyme and hydroxylamine reversed this inhibition, suggesting the involvement of a histidine residue in catalysis as expected for enzymes containing active serine. This thioesterase did not affect the chain length distribution of the products generated by the Euglena fatty acid synthase I.

Cysteine conjugate beta-lyase in the gastrointestinal bacterium Fusobacterium necrophorum.

A cysteine conjugate beta-lyase from the anaerobic gastrointestinal bacterium Fusobacterium necrophorum was purified 51-fold by heat treatment, ammonium sulphate fractionation, gel-filtration chromatography, and anion-exchange chromatography. This enzyme catalyses the cleavage of the thioether linkage in cysteine conjugates of the following S-alkyl- or S-aryl-linked compounds: cysteine conjugate of propachlor (2-S-cysteinyl-N-isopropylacetanilide); 1,2-dihydro-1-hydroxy-2-S-cysteinylnaphthalene and S-(2-benzothiazolyl)cysteine. 2-Mercapto-N-isopropylacetanilide, pyruvic acid and ammonia were produced from the beta-lyase cleavage of the cysteine conjugate of propachlor in equimolar ratios. The apparent Km values for the cysteine conjugate of propachlor and S-(benzothiazolyl)cysteine were 1.1 and 1.0 mM, respectively. Pyridoxal phosphate was required for enzymic activity. Ammonium ion activated enzymic activity, while hydroxylamine completely inhibited the enzyme. Dithiothreitol and bovine serum albumin had no effect on enzymic activity.

Influence of monovalent cations on rat alpha- and beta-parvalbumin stabilities.

The mammalian genome encodes both alpha- and beta-parvalbumin isoforms. The rat beta-parvalbumin (aka "oncomodulin") is more stable than the alpha isoform at physiological pH and ionic strength, despite its substantially higher charge density and truncated C-terminal helix [Henzl, M. T., and Graham, J. S. (1999) FEBS Lett. 442, 241-245]. Reasoning that solvent interactions could contribute to this unexpected finding, we have examined the stabilities of the Ca(2+)-free alpha- and beta-parvalbumins as a function of Na(+) and K(+) concentration. Differential scanning calorimetry data suggest that, at physiological pH and ionic strength, the beta isoform binds roughly 2 equiv of Na(+) or a single equivalent of K(+) with moderate affinity. Under comparable conditions, the alpha isoform apparently binds just 1 equiv of Na(+) and essentially no K(+). Isothermal titration calorimetry experiments suggest that the bound monovalent ions occupy the EF-hand motifs. In 0.15 M K(+), at pH 7.4, the stability of the apo-beta-parvalbumin exceeds that of the alpha isoform by approximately 2.6 kcal/mol at 37 degrees C and by approximately 3.0 kcal/mol at 25 degrees C. The latter value represents a substantial fraction of the difference in Ca(2+)-binding free energies measured in vitro for the two proteins. Significantly, however, these results do not completely explain the paradoxical stability of the beta isoform, which maintains its higher melting temperature under all conditions examined.

Nuchal cord entanglements and gestational age.

The purpose of this observational study was to investigate the relation between nuchal cord entanglements and gestational age. Computerized data from our hospital perinatal database were reviewed between January 1990 and December 1994. Data from all deliveries > or = 20 weeks' gestation underwent either a Cochran-Mantel test for trend or Chi-square testing where appropriate. Of the 13,895 singleton deliveries, the finding of an entanglement increased significantly from 5.8% at 20 weeks to 29.0% at 42 weeks' gestation. The frequencies increased linearly, regardless of whether the entanglement involved a single loop (p < 0.001) or multiple loops (p < 0.002). The risk of an antepartum stillbirth was not increased in the presence of a nuchal cord entanglement, even after controlling for other risk factors. These normative data should serve as a reference for prenatal ultrasound examinations and for prospective studies intended to evaluate the predictive value of reporting this finding prenatally.

Multiple nuchal cord entanglements and intrapartum complications.

OBJECTIVE: Our purpose was to evaluate the outcomes of pregnancies complicated by a multiple (double, triple, or quadruple) nuchal cord entanglement. STUDY DESIGN: Computerized data from our University Hospital perinatal database were reviewed between 1990 and 1994. Only singleton, vertex, and term pregnancies undergoing labor were analyzed. Patients with active perinatal complications were eliminated to reduce bias. Pregnancies with infants with either a single or no nuchal cord entanglement served as comparison groups. A comparison of frequencies in the three groups was by chi 2 testing and a comparison of means by a two-tailed Student t test and analysis of variance. RESULTS: Of the 8565 deliveries, the frequency of two or more cord entanglements at delivery was 3.8%. Compared with a single or no cord entanglement, pregnancies with a multiple entanglement were more likely to exhibit an abnormal fetal heart rate pattern during advanced labor (p < 0.001) and to require low or midforceps application (p < 0.001). The study infants were also more likely to have meconium (p = 0.013), a low 1-minute Apgar score (p < 0.001), and an umbilical artery pH < or = 7.10 (odds ratio 2.2, p = 0.013) than the controls. Rates of abruptio placentae, cesarean delivery, and 5-minute Apgar scores < 7 were no more common in the multiple entanglement than the control groups. CONCLUSION: A multiple nuchal cord entanglement was associated with a greater risk of meconium, an abnormal fetal heart rate pattern during advanced labor, the need for operative vaginal delivery, and mild umbilical artery acidosis at birth; however, there was no added risk of an adverse neonatal outcome.

Effects of intracervical prostaglandin E2 on fetal heart rate and uterine activity patterns in the presence of oligohydramnios.

OBJECTIVE: Our purpose was to compare fetal heart rate patterns and uterine activity before and after preinduction prostaglandin E2 administration in the presence or absence of oligohydramnios. STUDY DESIGN: In a retrospective case-controlled review we examined cases in which prostaglandin E2 (Prepidil) was inserted intracervically for gravid women requiring an induction of labor in the presence of either oligohydramnios (amniotic fluid index < or = 5.0) or adequate fluid (amniotic fluid index 5.1 to 23.9). Uterine activity and fetal heart rate tracings that were begun 1 hour before and continued for 6 hours after dosing were interpreted without knowledge of amniotic fluid volume. RESULTS: Cases in the oligohydramnios (n = 51) and adequate fluid (n = 49) groups were the same for maternal age, race, parity, gestational age, and predose Bishop score. Patients with oligohydramnios had more high-amplitude contractions in the first hour after dosing (9.0 +/- 1.2 vs 6.1 +/- 0.9, p < 0.05), but there were no significant differences in the frequency or duration of contractions during the subsequent 5 hours. Uterine hyperstimulation was not seen, and there were no differences in the frequency of variable or late fetal heart rate decelerations. CONCLUSION: For pregnancies undergoing preinduction cervical ripening with intracervical prostaglandin E2, the presence of oligohydramnios was not associated with a greater risk of fetal heart rate decelerations, although contractions were more common during the first hour after dosing.